1. Field of the Invention
The present invention relates to a liquid crystal display apparatus and, more specifically, relates to a liquid crystal display apparatus including a reflective part and a transmissive part in a liquid crystal cell.
2. Description of the Related Art
In the field of display devices, active matrix display apparatuses that have high display quality are widely used. An active matrix display includes a plurality of pixel electrodes. Each of these pixel electrodes are provided with a switching element. In this way, each pixel electrode can be reliably switched. Consequently, a large-size display apparatus having high resolution can be provided.
Recently, there has been a need for display apparatuses that consume less power and have a brighter display with a larger pixel area. Accordingly, a display apparatus including an active matrix substrate that is entirely covered with a thick insulating layer and including reflective pixel electrodes disposed on this insulating layer has been put to practical use. For such a display apparatus that includes an insulating layer with pixel electrodes, electrical short-circuiting between scanning lines and signal lines provided below the insulating layer and the pixel electrodes on the insulating layer can be prevented. In this way, the pixel electrodes can be provided in a large area in a manner such that the pixel electrodes overlap the wiring. Consequently, most of the areas including the switching elements, such as thin film transistors (TFTs), the scanning lines, and the signal lines can be used as pixel areas that contribute to the display. Thus, the aperture ratio is increased, and the display becomes bright.
Since liquid crystal display apparatuses using only reflective pixel electrodes cannot be used in a dark area, semi-transmissive liquid crystal display apparatuses are put to wide use. A semi-transmissive liquid crystal display apparatus includes a backlight and has a structure that is the same as that of a reflective liquid crystal display apparatus capable of transmissive display in predetermined areas.
Lately, a liquid crystal display apparatus that is capable of operating in an optical compensated birefringence (OCB) mode has been drawing attention. In an OCB mode, gradation display is carried out by utilizing the facts that the liquid crystal molecules enter a bent state when a voltage is applied and the pretilt angle to the alignment direction gradually changes when the applied voltage is increased. In an OCB mode, response is fast and a large angle of visibility can be obtained.
Also, lately, as described in Japanese Unexamined Patent Application Publication No. 9-146086, a mode similar to an OCB mode has been proposed. In this mode similar to an OCB mode, liquid crystal molecules of a liquid crystal layer interposed between a pair of alignment films are in a hybrid state and one of the alignment films has a horizontal alignment whereas the other alignment film has a perpendicular alignment.